The present invention relates generally to crop harvesting machines, commonly referred to as mower-conditioners or windrowers and, more particularly, to conditioning rolls for use in such machines.
Mower-conditioners are well known in the agricultural industry, and may be found in various configurations and designs—the common functions including the severing of standing crop material from the ground, the feeding of cut crop material into a conditioner, and the depositing of the conditioned crop material onto the ground for drying. See, for example, pull-type (generally shown in U.S. Pat. No. 4,035,991), pivot tongue (generally shown in U.S. Pat. No. 5,778,647), and self-propelled (generally shown in U.S. Pat. No. 6,073,431). For purposes of providing a description of exemplary conditioner frames, torsion bars and other structure, the three patents mentioned in the immediately preceding sentence are incorporated in full herein by reference. The conditioning operation consists of passing the cut crop material between a pair of parallel co-acting rolls to break open the hard outer shell of the stems of the stalks to facilitate the escape of moisture from the interior of the stems. This enables the stems to dry, or cure, to the desired moisture content for further harvesting operations in substantially the same length of time as the leaves, thereby decreasing the harvesting time as well as yielding a more uniformly cured and more valuable harvested crop.
In the conditioning operation, the cut crop stalks normally pass between the conditioning rolls with the stems generally perpendicular to the axes of the rolls. One type of conditioning operation, known as crimping, employs a pair of rolls having narrow longitudinally extending radially fins. The two rolls are mounted on a frame such that the fins of the two rolls intermesh without touching. In passing between the intermeshing fins, the stem of the stalk is cracked open transversely at regular intervals along its length. Crimper rolls are characterized by their aggressive feeding and stem cracking action; however, they are rough and vibrant in operation and attack the stems only at spaced intervals, leaving pockets of trapped moisture between successive transverse cracks.
Another type of conditioning operation, known as crushing, employs a pair of relatively smooth rolls which co-act to crush the stems of stalks passing therebetween. In passing between the crushing rolls, the stem of a stalk is cracked open longitudinally along its full length, leaving no pockets of trapped moisture; however, neither the feeding action nor the stem cracking action of the crushing rolls is normally as aggressive as that of the crimper. Hence, a crusher is more apt than a crimper to become plugged. Many compromise designs have been employed, such as, for example, co-acting rolls of different diameters; and one smooth roll of steel for its crushing action, co-acting with another smooth roll of rubber, for its enhanced gripping action. Crusher rolls made of various materials and with various surface tread patterns have also been employed in an effort to increase the aggressiveness of the crusher.
Crop and operating conditions, of course, vary the full ranges from thin growth versus thick (i.e., light versus heavy), large diameter stalks versus small diameter, tall crops versus short, hard stalks versus soft, presence of leaves versus absence, wet crops versus dry, and the like. With each of these variations the farmer/operator seeks to locate or identify the most acceptable balance between aggressiveness of feed and conditioner performance that will still give him an efficient and effective crop harvest.
It would be advantageous to provide a conditioner that exhibits the proper balance between aggressive feeding and conditioning for the crops (and similar crops) identified immediately above while increasing the durability of the rolls.